Packaging material, in particular packaging laminate comprising a core of fibrous material, such as paper board or carton board is manufactured in sequential steps. The order of the steps, as well as the contents of a particular step may vary, yet as an example the process may start with the production of the board.
The board is produced in a paper mill and rolled onto large-sized rolls and shipped to a converting facility. In the converting facility the large-size rolls are unrolled and additional layers, usually plastics and or aluminium foil, is extruded (or laminated) onto the surfaces of the board, and rolled onto a new roll. In the same, or in a previous or a subsequent the web of material may also be provided with a suitable décor and crease lines, i.e. weakening lines providing guides when a subsequent packaging container is to be folded.
At some step during the process the first large-size roll is divided into multiple rolls in a width direction. The resulting rolls may typically have a width corresponding to a crease pattern in a first direction for a single packaging container and a length corresponding to the crease patterns in a second direction for a specific number of packaging containers. The specific number is typically in the order to thousands of packaging containers, but there is obviously a maximum amount of packaging containers that could be fitted onto a single roll.
The above process is described in a rudimentary manner, and more information should be readily available to the skilled person. In EP1184311 by the present applicant additional background information may be found.
In the cited application some examples of where splicing may be applied is given, and while that application describes splicing in a filling machine splicing may be and is applied in any step of the manufacture of roll of packaging material. Typical examples are when an additional length of packaging material has to be added to an existing roll, and when a portion of the web has been removed since it contains a defect. The latter is often referred to as “doctoring”.
Paraphrasing the background section of another application to the present applicant, namely WO03106315, may act as a suitable background description for the present application as well:
Packs for liquid foods, for example juices or milk, are known, comprising plastic-coated paper, cardboard or generally a coated fibre layer. Such packs are produced in known filling machines from individual rolls from which the respective material web is drawn. Such individual rolls comprise a wound material web which is previously embossed, stamped, laminated and so forth. The filling machine continuously produces the liquid packs, with the material web being continuously withdrawn from the individual roll. When the individual roll is exhausted, a reserve roll must be in readiness in good time and the trailing edge of the ‘old’ material web of the exhausted individual roll must be joined to the pre-prepared leading edge of the new individual roll. That method of joining the two material webs is also referred to as ‘splicing’.
In regard to processing individual rolls in filling machines, it is also known that a cut, open edge of the fibre layer, for example the paper layer, leads to swelling and a loss of sealing integrity upon coming into contact with the packaged liquid.
Therefore previously cited EP1184311 already discloses a method of providing one of the two transverse edges of the material webs with an inclined cut and then, with the acutely terminating edge of the material web being bent over, glueing it in such a way that a liquid-tight weld is provided on the product side. In that way the originally open surface of the fibre layer is covered by plastic material and liquid-tightly welded.
In the case of the individual rolls which are processed in filling machines, heat and pressure can be applied simultaneously over the complete width of the material web by clamping a first bar against a second one, so that, in combination with the inclined cut, it is possible to produce liquid-tight packs.
The individual rolls are produced by cutting machines which make it possible to cut the desired number of individual rolls from a large wide master roll, after the steps of laminating, printing, coating and so forth.
The problem of the wide material web and thus exhaustion of the first roll is known. It was however hitherto difficult if not impossible for the trailing edge of a wide master roll to be glued to the leading transverse edge of the reserve master roll, for, by virtue of the width of for example 1.6 m of a master roll, it was not possible for pressure and heat to be applied in the correct amount and at the right time to the complete width of the transverse edge of a material web in such a way that it was possible to produce an adhesive join of good quality and with good liquid-tight sealing integrity.
At a subsequent time the smaller roll may be shipped to a filling machine where it is arranged in a packaging machine or filling machine, from which filled packaging containers are output.
Using the above as a starting point there are still improvements to be made. In that context it should be stated that any improvement in the area of splicing and similar operations may have a direct impact on the time spent on the operation, on the quality of the result on the amount of waste generated in downstream processes etc.
The present disclosure aims at providing a new method and device for splicing, having the purpose of providing a high consistent performance and increased efficiency.